Sewing machine thread tensioning mechanism



@QL 9, 19.956 F. E. cam-2 SEWING MACHINE THREAD TENSIONING MECHANISM 5 Sheets-Sheet l Original Filed Oct. 16, 1955 0 w mw w WM w w M Il l 6 a 5 n L-- 9J M L /On/ o Q m l ww 2 c 6 l a w M J R u. 3 2 G 0 0 0 2 n0 n@ 6 a, a Aa a@ 6 w w w 012t- 9, 1956 F. E. COLE SEWING MACHINE THREAD TENSIONING MECHANISM 3 Sheets-Sheet 2 Original Filed Oct.. 16, 1953 Il llll Oct. 9, 1956 F. E. COLE SEWING MACHINE THREAD TENSIONING MECHANISM Original Filed OGL 16, 1955 3 Sheets-Sheet 3 SEWING MACHINE THREAD TENSIONING MECHANISM Frank E. Cole, Manchester, Mass., assignor to United Shoe Machinery Corporation, Boston, Mass., a corporation of New Jersey Original application October 16, 1953, Serial No. 386,551. Divided and this application April 1955, Serial No. 501,688

4 Claims. (Cl. lll-59) The present invention relates to a thread tensioning mechanism in a sewing machine, and more particularly to a thread tension gauge tester adapted for measuring the tension imposed upon the thread in the machine.

lt is a principal `object of the invention to improve the construction and operation of the inseam sewing mechanism of the machine with particular reference to the devices for tensioning the thread.

More specifically it is an object of the invention to provide means readily available to the operator for accurately measuring the tension which is imposed on the thread by the tension device at any desired point in the machine operation.

With the above and other objects in view which may hereinafter appear a feature of the invention consists in the provision of a novel device for gauging and adjusting the amount of the tension imposed upon the thread by the thread tensioning device of the machine. The tension gauge tester employed takes the form of a rotatably supported gauging member which is axially shiftable into clutching engagement with the tension wheel brake drum of the machine. A manually operable gauging arm is pivotally mounted on the gauging member and is yieldably supported to turn therewith by means of a calibrated spring. The tension gauge tester enables the operator quickly and accurately to set the thread tension at any desired value in accordance with the weight and quality of thread being used in the machine.

The several features of the invention consist also in the devices, combinations and arrangement of parts hereinafter described and claimed which, together with the advantages to be obtained thereby, will be readily understood by one skilled in the art from the following description taken in connection with the accompanying drawings, in which:

Fig. l is a View in front elevation of the machine head;

Fig. 2 is a view looking from the left of substantially the parts Ishown in Fig. l;

Fig. 3 is a detail View in front elevation of the thread tension wheel, the tension brake, and the tension gauge tester shown in Fig. 1, but with the tension gauge tester moved to its operative position;

Fig. 4 is a view looking from the left, `of the parts shown in Fig. 3; and

Fig. 5 is a sectional view taken on line 5-5 of Fig. 4.

The invention is herein disclosed as embodied in an automatic shoe machine of the general description having a welt sewing mechanism, an inseam trimming mechanism, a shoe supporting jack, and jack supporting and pattern mechanism. For a description of this Amachine reference may be had to applicants copending application for Letters Patent in the United States Patent Oflice Serial No. 386,551, tiled October 16, 1953, for Shoe Machines, of which the present application is a division.

The operating devices of the machine include a chainstitch shoe sewing mechanism having a curved hook needle (not shown) movable in the line of feed, an oscil- 2,765,757 Patented Get. 9, 1956 latory looper 122 and a thread iinger 124 which is movable in a direction substantially parallel to the line of feed and away from the trimming knife of the machine, these parts being located entirely at that side of the sewing point away from the completed stitches of the seam to coopcrate with a rotary tubular knife which is of relatively large size with its axis parallel to the line of feed and with the cutting edge of the knife passing transversely across the sewn inseam.

The mechanisms for supporting and actuating the sewing instrumentalities of the illustrated machine are in genera-l similar to corresponding parts illustrated in applicants copending application Serial No. 386,551 above referred to, and to corresponding parts illustrated in the Morrill Patent No. 2,529,095 dated November 7, 1950. inasmuch as this mechanism has been previously shown and forms specifically no part of the present invention further illustration or description thereof is omitted herein.

The thread handling devices of the machine in addition to those previously enumerated include a thread take-up and a thread tensioning device. The thread take-up comprises a take-up lever 610 (Fig. 2) which is supported intermediate its length to turn on a pivot 612. At its forward end lever 610 carries a take-up roller 614, and at its rear end is provided with a cam follower roller 616.

The thread, drawn from a suitable source of supply, passes around a tension wheel 618 of conventional design, under a roller 620, over take-up roller 614, around rollers 622 and 624, and thence downwardly to the looper 122.

The thread tension and tension release mechanism of the machine is in general similar, except as hereinafter described, to the tension release mechanism illustrated in the U. S. Patent to Cole 2,465,356 dated March 29, 1949, for improvements in Tension Devices for Thread Handling Machines, but is shown and will be briefly described with reference to Figs. 1, 2, 3 and 4 of the drawings in order to indicate the connection of the present invention therewith, as follows:

The tension wheel 618 is secured to a shaft 62S mounted to turn in a bearing 636 having formed thereon a brake hub 632. A coil spring 634 supported on the brake hub 632 and connected at one end into a holder 636 and at its other end supported on a rearwardly extending tension release arm 638 (see Fig. 4) pivoted on the tension wheel shaft 628, is adapted for frictiona-l engagement with the brake hub 632 to apply a brake tension to the thread. The holder 636 is adjustably mounted on a lever support 637, which is supported coaxially with the take-up lever 610 and is adjustably secured by means of a pin-and-slot connection to turn therewith. The adjustment of lever support 637 with relation to the take-up lever 610 will effect an adjustment of the tension exerted by the brake spring 634. Adjustment in the position of holder 636 with relation to the lever support 637 serves to vary the amount of increase and decrease in tension which is effected by the up-and-down movement of the take-up lever 610.

The tension release arm 638 (Fig. 4) is connected by a link 640 with a forwardly extending latch arm 642 which is in turn mounted on the thread tension brake release rock shaft 505. When the machine is stopped, the rock shaft 505 is turned in a counterclockwise direction to the position shown in Fig. 2 so that the latch lever 642, link 640 and tension control arm 638 are raised, thus slightly uncoiling the spring 634 to release the tension on the tension Wheel 618. The means for imparting this rocking movement to the rock shaft 505 comprises a stop arm, not specifically shown, which is pivoted on the rock shaft 505 and is moved counterclockwise to its stopped position by a cam on the cam shaft in stopping the machine. The tension brake release rock shaft 505 is permitted to return in a clockwise direction to its running position in which the tension release arm 63S is rocked downwardly to permit the coiled brake spring 634 to be brought into frictional engagement with the brake hub 632 when the machine is started, only after the iirst two stitches have been formed.

The return of the rock shaft 505 to its operating position is delayed by means of two latch mechanisms which operate successively to support the rock shaft 505 during the formation of the iirst two stitches. During the formation of the rst stitch the rock shaft is supported in its off position by means of a downwardly extending arm 644 which is engaged during the first cycle of the movement of the sewing mechanism by latch lever 646 (Fig. 2) which is arranged to be moved between a latching and an inoperative position by means of a cam on the lock bolt actuating bell crank 64S associated with the sewing machine stop motion. Thereafter, during the formation of the second stitch the tension brake release rock shaft 565 is held in its inoperative position by engagement of a depending latch 654) with the forward end of latch lever 642 until removed by the operation of a trip latch 652 which engages a notch 654 formed in the hub of the oscillating takeup lever 610.

With this construction and operation of the thread tension brake release mechanism, it will be evident that the microswitch 504 will be engaged by its actuating arm 563 on the tension brake release rock shaft 505 when the rock shaft is moved to its brake release position upon stopping of the sewing mechanism and will be moved away from the microswitch 504 to permit closing of the switch contact only when the rock shaft 505 is again moved to its thread tension applied position upon completion of the first two stitches of the seam.

In accordance with the invention there is provided in the present machine a tension gauge tester device which will enable the operator to gauge with accuracy the amount of tension applied by the tension brake and will thus permit the operator to adjust the strength of the brake tension applied against the thread in accordance with the known breaking strength of the particular thread being employed in the machine. The tension gauge tester device as best shown in Figs. 3 to 5 of the drawings comprises a bracket 656 which is supported on the machine frame and provides a bearing for an axially shiftable plunger 653 in axial alignment with the tension wheel supporting shaft 628 and brake drum 632. A transverse pin 669 passing through the plunger 65S is arranged for clutching engagement with recesses formed in the hollowed end of the brake drum 632 when the plunger is moved axially into engagement therewith.

A coiled spring 662 between the sleeve hub of the bracket 656 and enlarged head 664 of the plunger serves normally to maintain the plunger in the retracted disengaged position in which the gauge tester is tipped upwardly and rearwardly to a rest position on the supporting bracket 656 as shown in Figs. l and 2. The gauge is mounted on the enlarged head 664 of the plunger and comprises an arm 666 formed integrally with the head 664 and at its outer end providing a bearing 668 for a pivoted gauge arm 670 which has formed thereon a cap 672 disposed directly over the enlarged head 664. A coiled compression spring 674 is mounted within the cap 672, having its axis disposed radially of the plunger and seated at one end in a cup-shaped member 676 which rests against the relatively stationary support provided by the head 664 and at its upper end seated against an abutment 678 adjustably supported within the cap by means of an adjusting screw 63) and nut 632. A pin 684 mounted in the side of the cap 672 and arranged for engagement in a slot formed in a vertically disposed plate 686 fastened to the end of the enlarged head 664 serves to limit the upward movement of the cap under pressure of the spring 674. Upward movement of the cap 672 and pivoted gauge arm 670 is limited also by means of a tie rod 688 which is arranged to extend through bores in the arm 666 and gauge arm 670 and is provided at one end with an enlarged head and at its other end with a nut. A manual control arm 690 is rigidly mounted on the pivoted gauge arm 670.

The operation of the tensioning gauge tester is briefly as follows: Assuming that it is desired to gauge the tension on the thread at the point of maximum tension, that is, when the take-up lever is at the top of its loop drawing stroke, the machine is stopped in this position with the tension applied. The gauge is now moved forwardly and down to its operative position and then inwardly so that the pin 660 is in clutching engagement with the brake drum 632. The handle 690 is now moved upwardly to turn the tension wheel shaft and the brake drum with relation to the brake spring 634. The resistance encountered to this movement of the hand lever 690 will cause the pivoted gauge arm 670 to be moved downwardly against the pressure of spring 674, so that a reading is obtained on calibrated scale markings which are applied on the cap 672 above the end of the cover plate 686. Similar readings may be obtained for the amount of tension applied to the thread at other points in the sewing cycle by turning the machine to the desired position and thereafter proceeding with the operation of the gauge tester as above described.

It will be understood that the gauge tester employed herewith, while not limited in its application to the particular construction shown, has been found to be particularly valuable when used in combination with a thread tension device in which inertia and the usual variable components of friction for starting and running are substantially eliminated so that the reading obtained constitutes an accurate measure of the tension imposed upon the thread by the tension device during the operation of the machine at relatively high speeds. The gauge tester disclosed has the further advantage that it permits an accurate adjustment of the spring tension without the necessity of Calibrating the tension brake spring 634. It is assumed that the gauge tester spring 674 will be chosen and the tester will be calibrated to give readings from tive to fifty pounds in order to take care of different types of thread which may be expected to be used on an inseam sewing machine.

The invention having been described what is claimed l. In a shoe sewing machine, the combination with thread handling devices including a thread tensioning device comprising a thread traction member, a thread tension brake drum connected to turn with the traction member and a friction brake element arranged for engagement with the drum, of a thread tension gauge tester comprising a torque measuring gauge supported on the machine, and means for connecting the torque measuring gauge to rotate the drum.

2. In a shoe sewing machine, thread handling devices including a thread tensioning device comprising a thread traction member, a thread tension brake drum connected to turn with the traction member and a friction brake element arranged for engagement with the drum, a thread tension gauge tester comprising a gauge member rotatably supported on the machine, means for connecting the member to rotate the brake drum, a manually operable handle supported on the gauge member for rotating the gauge member, and pressure responsive gauging means connecting said member and handle for gauging the turning pressure exerted on the gauging member by said handle.

3. In a shoe sewing machine in which the sewing instrumentalities include a needle, a thread take-up and a thread tension device including a thread traction member, a tension brake drum connected to turn with the traction member and a wrap spring friction brake element for engagement with the drum, a thread tension gauge tester which comprises a gauging member rotatably supported on the machine in alignment with the brake drum, a clutching device through which the gauging member is connected to `turn with the brake drum, a gauging arm on the gauging member for rotating said member, a supporting pivot on the member parallel to the rotational axis of the gauging member, and pressure responsive gauging means connecting said member and arm for gauging the turning pressure exerted on said member by the arm.

4. In a shoe sewing machine of which the `thread handling devices include a thread tensioning device comprising a thread traction member, a tension brake drum connected to turn therewith and a friction brake element engaging the drum, a thread tension gauge tester which comprises a gauging member supported for rotational and axial movement on the machine in axial alignment with the brake drum, cooperating clutching surfaces for connecting the gauging member to rotate the drum, a gauging arm including a manually operable handle supported on the member to turn about an axis parallel to the rotational axis of said member, spring means connecting said member and arm, and visual indicating means associated therewith for gauging the turning pressure exerted on the gauging member by said handle.

References Cited in the iile of this patent UNITED STATES PATENTS 2,000,613 Ricks et al May 7, 1935 2,032,311 Ricks et al Feb. 25, 1936 2,465,356 Cole Mar. 29, 1949 

